feat: populate note files with problem descriptions and code stubs

Add populate-notes.mjs that fetches problem descriptions and
Python/C++ code stubs from LeetCode's GraphQL API. Populated
all 197 NeetCode 150 note files with:
- Problem description (examples, constraints)
- Python code stub (function signature)
- C++ code stub (function signature + includes)

API responses cached in leetcode/.cache/leetcode/ for instant re-runs.

org/study_deck_02/dsa/intervals/0057-insert-interval.org

@@ -1,18 +1,65 @@
 #+PROPERTY: STUDY_DECK_02
 * TODO 0057. Insert Interval :medium:
 :PROPERTIES:
-:NEETCODE: [[file:../../roadmap.org::*0057. Insert Interval][Roadmap]]
+:NEETCODE: [[file:../../roadmap.org::*0057. Insert Interval][0057. Insert Interval]]
 :END:
 
+You are given an array of non-overlapping intervals ~intervals~ where ~intervals[i] = [start_{i}, end_{i}]~ represent the start and the end of the ~i^{th}~ interval and ~intervals~ is sorted in ascending order by ~start_{i}~. You are also given an interval ~newInterval = [start, end]~ that represents the start and end of another interval.
+
+Insert ~newInterval~ into ~intervals~ such that ~intervals~ is still sorted in ascending order by ~start_{i}~ and ~intervals~ still does not have any overlapping intervals (merge overlapping intervals if necessary).
+
+Return ~intervals~/ after the insertion/.
+
+*Note* that you don't need to modify ~intervals~ in-place. You can make a new array and return it.
+
+*Example 1:*
+
+
+#+begin_src
+Input: intervals = [[1,3],[6,9]], newInterval = [2,5]
+Output: [[1,5],[6,9]]
+#+end_src
+
+
+*Example 2:*
+
+
+#+begin_src
+Input: intervals = [[1,2],[3,5],[6,7],[8,10],[12,16]], newInterval = [4,8]
+Output: [[1,2],[3,10],[12,16]]
+Explanation: Because the new interval [4,8] overlaps with [3,5],[6,7],[8,10].
+#+end_src
+
+
+*Constraints:*
+
+ - ~0 <= intervals.length <= 10^{4}~
+
+ - ~intervals[i].length == 2~
+
+ - ~0 <= start_{i} <= end_{i} <= 10^{5}~
+
+ - ~intervals~ is sorted by ~start_{i}~ in *ascending* order.
+
+ - ~newInterval.length == 2~
+
+ - ~0 <= start <= end <= 10^{5}~
+
 ** TODO Approach
 Write your approach here.
 
 ** TODO Python
 #+begin_src python
-
+class Solution:
+    def insert(self, intervals: List[List[int]], newInterval: List[int]) -> List[List[int]]:
 #+end_src
 
 ** TODO C++
 #+begin_src cpp
-
+class Solution {
+public:
+    vector<vector<int>> insert(vector<vector<int>>& intervals, vector<int>& newInterval) {
+        
+    }
+};
 #+end_src